Fastening devices for explosion-proof enclosures

ABSTRACT

A system for fastening a cover to a body of an explosion-proof enclosure using a plurality of fastening devices. Each fastening device can include a first load distributing member disposed on a body flange of a body of the explosion-proof enclosure. Each fastening device can also include a second load distributing member disposed on a cover flange of a cover of the explosion-proof enclosure. Each fastening device can further include a fastener positioned atop the first load distributing member, where the fastener traverses the first load distributing member, the cover flange, and the body flange. Each fastening device can also include a fastener receiver positioned under the second load distributing member and mechanically coupled to the fastener.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of and claims priorityunder 35 U.S.C. §121 to U.S. patent application Ser. No. 13/793,774,entitled “Fastening Devices for Explosion-Proof Enclosures” and filed onMar. 11, 2013, which itself claims priority under 35 U.S.C. §119 to U.S.Provisional Patent Application Ser. No. 61/640,827, titled “FasteningDevices for Explosion-Proof Enclosures” and filed on May 1, 2012. Theentire contents of these two applications are hereby incorporated hereinby reference.

The present application is further related to U.S. patent applicationSer. No. 13/793,672, entitled “Fastening Devices for Explosion-ProofEnclosures,” whose entire contents are hereby incorporated herein byreference.

The present application is further related to U.S. patent applicationSer. No. 13/794,402, entitled “Fastening Devices for Explosion-ProofEnclosures,” whose entire contents are hereby incorporated herein byreference.

The present application is further related to U.S. patent applicationSer. No. 13/794,433, entitled “Cover Release Mechanisms for Enclosures,”whose entire contents are hereby incorporated herein by reference.

The present application is further related to World IntellectualProperty Organization (WIPO) Patent Application Serial NumberWO2011/084152, titled “Enclosure Clamps and Clamp Systems,” filed onJan. 5, 2010, and whose entire contents are hereby incorporated hereinby reference.

The present application is further related to a patent applicationtitled “Fastening Devices for Explosion-Proof Enclosures,” having Ser.No. 14/327,445, which is being filed concurrently with the U.S. Patentand Trademark Office, and whose entire contents are hereby incorporatedherein by reference.

TECHNICAL FIELD

The present disclosure relates generally to explosion-proof enclosuresand/or flame-proof, and more particularly to systems, methods, anddevices for securing a cover of an explosion-proof enclosure to a bodyof the explosion-proof enclosure.

BACKGROUND

Explosion-proof receptacle housings and enclosure systems are used inmany different industrial applications. Such explosion-proof receptaclehousing and enclosure systems may be used, for example, in militaryapplications, onboard ships, assembly plants, power plants, oilrefineries, petrochemical plants, and other harsh environments. Attimes, the equipment located inside such explosion-proof receptaclehousing and enclosure systems is used to control motors and otherindustrial equipment.

In order for an explosion-proof enclosure to meet certain standards andrequirements, the cover of the enclosure must be sealed to the body ofthe enclosure within certain tolerances. Often, this requires a largenumber (30 or more) of bolts to be tightened. Consequently, securing allof the bolts at the appropriate torque is a very time-consuming process.In addition, removing all of the bolts to access one or more componentsinside the explosion-proof enclosure is a time-consuming process.

SUMMARY

In general, in one aspect, the disclosure relates to a system forfastening a cover to a body of an explosion-proof enclosure using anumber of fastening devices. Each fastening device can include afastener that includes a stem having quick release threads, where thestem traverses a first aperture in a flange and a second aperture in anopposing flange. The fastener of each fastening device can also includea head rotatably coupled to the stem, where the head has mating threadsfor the quick release threads of the stem, and where the head abutsagainst the opposing flange.

In another aspect, the disclosure can generally relate to a system forfastening a cover to a body of an explosion-proof enclosure. The systemcan include a flange having a number of first apertures traversingtherethrough. The system can also include an opposing flange that abutsthe flange, where the opposing flange has a number of second aperturestraversing therethrough. The system can further include a number offastening devices. Each fastening device can include a fastener receiverdisposed on the opposing flange, where the fastener receiver has matingthreads. Each fastening device can also include a fastener having aproximal end and a distal end, where the proximal end abuts the flange,where the fastener traverses a first aperture and a second aperture,where the distal end comprises quick release threads disposed thereon,and where the quick release threads are threadably coupled to the matingthreads of the fastener receiver

In yet another aspect, the disclosure can generally relate to a systemfor fastening a cover to a body of an explosion-proof enclosure. Thesystem can include a flange having a plurality of slotted aperturestraversing therethrough. The system can also include an opposing flangethat abuts the flange, where the opposing flange has an anchor receiver.The system can further include a number of fastening devices. Eachfastening device can include a stem that moves within a slotted apertureof the slotted apertures, where the stem has a bolt length greater thana flange height. Each fastening device can also include a headmechanically coupled to a distal end of the stem and that abuts againstan outer surface of the flange. Each fastening device can furtherinclude an anchor movably coupled within the anchor receiver of theopposing flange and mechanically coupled to a proximal end of the stem.

In still another aspect, the disclosure can generally relate to a systemfor fastening a cover to a body of an explosion-proof enclosure. Thesystem can include a flange, and an opposing flange that abuts theflange. The system can also include a first load distributing memberdisposed on the flange, where the first load distributing member has anumber of slotted apertures traversing therethrough. The system canfurther include a second load distributing member disposed on theopposing flange, where the second load has an anchor receiver. Thesystem can also include a number of fastening devices. Each fasteningdevice can include a stem that moves within a slotted aperture of theplurality of slotted apertures, where the stem has a bolt length greaterthan a flange height, an opposing flange height, and a first loaddistributing member height. Each fastening device can also include ahead mechanically coupled to a distal end of the stem and that abutsagainst an outer surface of the flange. Each fastening device canfurther include an anchor disposed within and movably coupled to theanchor receiver of the second load distributing member, where the anchoris also mechanically coupled to a proximal end of the stem.

In yet another aspect, the disclosure can generally relate to a systemfor fastening a cover to a body of an explosion-proof enclosure using anumber of fastening devices. Each fastening device can include a camfixture having a cam slot, a first aperture, and a cam feature, wherethe cam fixture is disposed on a flange of the explosion-proofenclosure. Each fastening device can also include a fastener movablycoupled to the cam fixture within the first aperture, where the fastenerhas a stem, a head, and a base, where the head is mechanically coupledto one end of the stem, where the base is mechanically coupled to anopposite end of the stem, and where the base fits within the cam slotand rotatably couples to the cam fixture. The stem can traverse a secondaperture in an opposing flange of the explosion-proof enclosure. Thehead can abut against the opposing flange.

These and other aspects, objects, features, and embodiments will beapparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate only example embodiments of fastening devicesfor explosion-proof enclosures and are therefore not to be consideredlimiting of its scope, as fastening devices for explosion-proofenclosures may admit to other equally effective embodiments. Theelements and features shown in the drawings are not necessarily toscale, emphasis instead being placed upon clearly illustrating theprinciples of the example embodiments. Additionally, certain dimensionsor positionings may be exaggerated to help visually convey suchprinciples. In the drawings, reference numerals designate like orcorresponding, but not necessarily identical, elements.

FIGS. 1A and 1B show various views of example fastening devices inaccordance with certain example embodiments.

FIGS. 2A-2C show various views of alternative example fastening devicesin accordance with certain example embodiments.

FIG. 3 shows another alternative example fastening device in accordancewith certain example embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The example embodiments discussed herein are directed to systems,apparatuses, and methods of fastening a cover of an explosion-proofenclosure to a body of the explosion-proof enclosure. While the exampleembodiments discussed herein are with reference to explosion-proofenclosures, other types of non-explosion-proof enclosures (e.g.,junction boxes, control panels, lighting panels, motor control centers,switchgear cabinets, relay cabinets) or any other type of enclosure(e.g., a flame-proof enclosure) may be used in conjunction with exampleembodiments of fastening devices.

In one or more example embodiments, an explosion-proof enclosure (alsoknown as a flame-proof enclosure) is an enclosure that is configured tocontain an explosion that originates inside the enclosure. Further, theexplosion-proof enclosure is configured to allow gases from inside theenclosure to escape across joints of the enclosure and cool as the gasesexit the explosion-proof enclosure. The joints are also known as flamepaths and exist where two surfaces meet and provide a path, from insidethe explosion-proof enclosure to outside the explosion-proof enclosure,along which one or more gases may travel. A joint may be a mating of anytwo or more surfaces. Each surface may be any type of surface, includingbut not limited to a flat surface, a threaded surface, and a serratedsurface.

In one or more example embodiments, an explosion-proof enclosure issubject to meeting certain standards and/or requirements. For example,NEMA sets standards with which an enclosure must comply in order toqualify as an explosion-proof enclosure. Specifically, NEMA Type 7, Type8, Type 9, and Type 10 enclosures set standards with which anexplosion-proof enclosure within a hazardous location must comply. Forexample, a NEMA Type 7 standard applies to enclosures constructed forindoor use in certain hazardous locations. Hazardous locations may bedefined by one or more of a number of authorities, including but notlimited to the National Electric Code (e.g., Class 1, Division I) andUnderwriters' Laboratories, Inc. (UL) (e.g., UL 1203). For example, aClass 1 hazardous area under the National Electric Code is an area inwhich flammable gases or vapors may be present in the air in sufficientquantities to be explosive.

As a specific example, NEMA standards for an explosion-proof enclosureof a certain size or range of sizes may require that in a Group B,Division 1 area, any flame path of an explosion-proof enclosure must beat least 1 inch long (continuous and without interruption), and the gapbetween the surfaces cannot exceed 0.0015 inches. Standards created andmaintained by NEMA may be found at www.nema.org/stds and are herebyincorporated by reference.

Some standards also require that one or more tools are used to open anexplosion-proof enclosure. Example embodiments described herein requirethe use of a tool, whether custom made or standard, to disengage thefastening device and open the explosion-proof enclosure. Each of thecomponents of the example fastening devices (e.g., fastener, fastenerreceiver, load distributing member, handle, cam, pin) can be made fromone or more of a number of suitable materials, including but not limitedto stainless steel, plastic, aluminum, ceramic, rubber, and iron.

Example embodiments of fastening devices for explosion-proof enclosureswill be described more fully hereinafter with reference to theaccompanying drawings, in which example embodiments of fastening devicesfor explosion-proof enclosures are shown. Fastening devices forexplosion-proof enclosures may, however, be embodied in many differentforms and should not be construed as limited to the example embodimentsset forth herein. Rather, these example embodiments are provided so thatthis disclosure will be thorough and complete, and will fully convey thescope of fastening devices for explosion-proof enclosures to those orordinary skill in the art. Like, but not necessarily the same, elements(also sometimes called components) in the various figures are denoted bylike reference numerals for consistency.

FIGS. 1A and 1B show various views of an enclosure system 100 that usesan example fastening device 110 in accordance with one or more exampleembodiments. Specifically, FIG. 1A shows a front view of the enclosuresystem 100. FIG. 1B shows a cross-sectional top view of the examplefastening device 110. In one or more embodiments, one or more of thefeatures shown in FIGS. 1A and 1B may be omitted, repeated, and/orsubstituted. Accordingly, embodiments of fastening devices forexplosion-proof enclosures should not be considered limited to thespecific arrangements of components shown in FIGS. 1A and 1B.

Referring to FIGS. 1A and 1B, the enclosure system 100 of FIG. 1Aincludes an explosion-proof enclosure 103 using at least one examplefastening device 110 in accordance with certain example embodiments. Theexplosion-proof enclosure 103 includes an enclosure cover and a coverflange 122 around the perimeter of the enclosure cover. The cover flange122 is mated to (abuts against) a body flange 132 that is positionedaround the perimeter of the enclosure body. The cover flange 122 and thebody flange 132 each have a height or thickness, which may be the sameor different from each other. In certain embodiments, one or more hingesmay be positioned along one side of the enclosure cover and acorresponding side of the enclosure body. When most, if not all, of theexample fastening devices 110 are removed, the enclosure cover can beseparated from the enclosure body.

As shown in FIG. 1A, the example fastening device 110 is arranged aroundthe perimeter of the cover flange 122 and the body flange 132. The airgap that forms between the surfaces of the cover flange 122 and the bodyflange 132 when the cover flange 122 and the body flange 132 converge isthe flame path 169. One of the functions of the fastening device 110 isto ensure that the flame path 169 is within an accepted tolerance inlight of a particular standard for the explosion-proof enclosure 103.

As shown in FIGS. 1A and 1B, the fastening device 110 uses a quickrelease fastener 109, which includes a head 115 and a threaded stem 118.The head 115 can be shaped and/or configured to accommodate one or moreof a number of tools. For example, the head 115, when looking fromabove, may be shaped like a hexagon. As another example, the head 115may have a slot that traverses the top surface.

The threads 125 on the threaded stem 118 may be disposed along all or aportion of the surface of the threaded stem 118. In certain exampleembodiments, the threads 125 on the threaded stem 118 have a substantialthread profile. In other words, the shape and/or pitch of the threads125 are extreme so that the quick release fastener 109 can be secured toa fastener receiver 120 by rotating the quick release fastener 109approximately 90°. Such rotation can be clockwise or counterclockwise,depending on whether the threads 125 are left-handed or right handed.

The term “quick release” is meant to generally define fasteners that cantake less than one full turn of travel to reach optimal tension. Suchthreads on a quick release fastener can be called quick release threads.For example, the quick release fastener can travel 90° to reach the endof the mating thread to which the quick release threads of the quickrelease fastener are threadably coupled. Alternatively, the quickrelease fastener can travel any other distance, including but notlimited to approximately 45°, 180°, and 270°. In certain exampleembodiments, the quick release fastener can travel more than one turn(greater than 360°).

In addition, or in the alternative, the threads 125 on the threaded stem118 can be interrupted. In other words, each of the threads 125 on thethreaded stem 118 may not continue around the entire perimeter of thethreaded stem 118. The threads 125 on the threaded stem 118 can also, orin the alternative, have multiple lead threads (e.g., triple leadthreads, quad lead threads). In certain example, embodiments, the quickrelease fastener 109 is secured to the fastener receiver 120 by rotatingthe quick release fastener 109 less than 90°. For example, the quickrelease fastener 109 can be secured to the fastener receiver 120 byrotating the quick release fastener 109 approximately 45°.

The fastener receiver 120 can be secured to the body flange 132 or thecover flange 122 using an aperture in the body flange 132 or the coverflange 122, where the aperture is shaped to fit the fastener receiver120 without allowing the fastener receiver 120 to move transversely asthe quick release fastener 109 is coupled to the fastener receiver 120.In certain example embodiments, the fastener receiver 120 is integratedwith the body flange 132 and/or the cover flange 122, where the matingthreads 126 are machined into the body flange 132 and/or the coverflange 122.

If the fastener receiver 120 is a separate component from the bodyflange 132 and/or the cover flange 122 (i.e., if the fastener receiver120 is not integrated with the body flange 132 and/or the cover flange122), the fastener receiver 120 can have a shape that corresponds to ashape of the body flange 132 and/or the cover flange 122 into which thefastener receiver 120 is disposed. Examples of such shapes can include,but are not limited to, a triangle, a square, and a hexagon. Such ashape can be symmetrical, asymmetrical, or random.

In certain example embodiments, the mating threads 126 of the fastenerreceiver 120 can mate with the threads 125 of the threaded stem 118. Inaddition, the fastener receiver 120 can have one or more additionalfeatures. For example, as shown in FIG. 1B, the fastener receiver 120can have one or more of a number of stops 124 that prevent the threadedstem 118 from turning beyond a certain angle (e.g., 90°, 45°). In thiscase, as shown in FIG. 1B, each stop 124 can impede the rotational pathof a thread 125 (specifically, the distal portion of the thread 125) ofthe threaded stem 118. As another example, the fastener receiver 120 canhave one or more of a number of passages 140 that provide clearance forinsertion and/or extraction of the threaded stem 118 when the matingthreads 126 are disengaged from the threads 125 of the threaded stem118.

In certain example embodiments, the fastener receiver 120 can include atop portion and a bottom portion. As shown in FIG. 1A, the top portionof the fastener receiver 120 can be disposed within a cavity (hiddenfrom view of the fastener receiver 120) of the body flange 132. The topportion of the fastener receiver 120 can have a cross-sectional shapeand size that is substantially the same shape and size as a cavity inthe body flange 132. In certain example embodiments, the cavity thatreceives the top portion of the fastener receiver 120 is disposed in thecover flange 122 rather than the body flange 132. In such a case, theorientation of the fastener receiver 120 is inverted from its positionshown in FIG. 1A. In some cases, the cavity can completely traverse thebase flange 132 (or the cover flange 122) and partially traverse thecover flange 122 (or the base flange 132).

The cavity can be at least as long as the top portion of the fastenerreceiver 120. For example, as shown in FIG. 1A, the cavity issubstantially the same height as the height of the top portion of thefastener receiver 120. The walls of the flange (e.g., the body flange132, the cover flange 122) that form the cavity can be smooth, textured,and/or have some other feature (e.g., mating threads). Similarly, theouter surface of the top portion of the fastener receiver 120 can havethe same and/or different features. As an example, as shown in FIG. 1A,the wall of the body flange 132 that forms the cavity can have matingthreads 126 disposed thereon, and the outer surface of the top portionof the fastener receiver 120 can have corresponding mating threads(which can be the same or different than the threads 125) disposedthereon. As another example, the wall of the cover flange 122 can havethreads disposed thereon. In such a case, the threaded stem 118 can havecomplementary mating threads (which can be the same or different thanthe threads 125) disposed on its outer surface at an end opposite wherethe threads 125 are disposed. As a result, the head 115 can be anoptional feature of the quick release fastener 109.

In certain example embodiments, the bottom portion of the fastenerreceiver 120 can be wider (flared) compared to the top portion of thefastener receiver 120. In such a case, the flared bottom portion extendlaterally away from the top portion of the fastener receiver 120,forming an angle with the top portion. Such an angle can be one or moreof a number of angles (e.g., 90°, 120°, 45°). In certain exampleembodiments, the angle formed by the flared portion of the bottomportion relative to the top portion can be such that the flared portionof the bottom portion of the fastener receiver 120 is substantiallyparallel to the bottom surface of the body flange 132 (or the topsurface of the cover flange 122, as appropriate) when the top portion ofthe fastener receiver 120 is mechanically coupled to the cavity.

When the fastener receiver 120 is disposed within the cavity, and whenthe threaded stem 118 is disposed within the aperture that traverses thefastener receiver 120, the head 115 of the fastener 109 can be rotatedin a direction (e.g., clockwise) to apply greater compressive force tothe fastener receiver 120, the body flange 132, and the cover flange122. Specifically, when the head 115 is rotated in a certain direction(e.g., clockwise), mating threads 125, 126 make up and pull the fastenerreceiver 120 upward toward the head 115. Conversely, as the head 115 isrotated in an opposite direction (e.g., counterclockwise), the fastenerreceiver 120 is pushed away from the head 115.

In certain example embodiments, the head 115 is mechanically coupled toa flange (e.g., the cover flange 122, the body flange 132). The head 115can be mechanically coupled to a flange in one or more of a number ofways. For example, the head 115 can have threads disposed along itsouter surface that threadably couple to corresponding mating threadsdisposed along the wall that forms the cavity of the flange into whichthe head 115 is disposed. As another example, the head 115 can bepress-fit into a flange. In certain example embodiments, the head 115becomes fixed in place (at least in one rotational direction) when thehead 115 is mechanically coupled to a flange. In such a case, byrotating the fastener receiver 120, the threaded stem 118 is put undertension, closing the flame path 169 and drawing the cover flange 122 andthe body flange 132 together.

The fastener receiver 120 can be made of one or more of a number ofmaterials. Examples of such materials can include, but are not limitedto, steel, rubber, nylon, and aluminum. In certain example embodiments,when the fastener receiver 120 is mechanically coupled to the fastener310 and one or both flanges, a flame path 169 between the cover flange122 and the body flange 132 can meet one or more applicable standards(e.g., the flame path 169 is no greater than 0.0015 inches).

FIGS. 2A-2C show various views of a system 200 that uses yet anotherexample fastening device 210, in accordance with certain exampleembodiments, to secure the explosion-proof enclosure 203. In one or moreembodiments, one or more of the features shown in FIGS. 2A-2C may beomitted, repeated, and/or substituted. Accordingly, embodiments offastening devices for explosion-proof enclosures should not beconsidered limited to the specific arrangements of components shown inFIGS. 2A-2C.

Referring to FIGS. 1A-2C, FIGS. 2A-2C show an example fastening device210. In this case, the example fastening device 210 includes a bolt 209having a head 215 that is fixedly coupled to a stem 218. The fasteningdevice 210 can also include an anchor 240 that is movably (e.g.,rotatably) coupled to the load distributing member 280 and the stem 218.In such a case, the load distributing member 280 can include an anchorreceiver into which the anchor 240 can be movably disposed.

In certain example embodiments, the load distributing member 280 is notincluded, in which case the anchor 240 can be movably coupled to ananchor receiver disposed within the body flange 232 (or the cover flange222 if the fastening device 210 is inverted relative to what is shown inFIG. 2A-2C). As another alternative, if the load distributing member 212is included and if the fastening device 210 is inverted, the loaddistributing member 212 can include an anchor receiver, and the anchor240 can be movably disposed within the anchor receiver of the loaddistributing member 212.

In certain example embodiments, the stem 218 is fixedly coupled (ratherthan moveably coupled) to the anchor 240 and movably (e.g., rotatably)coupled to the head 215. In such a case, the anchor 240 remainsrotatably coupled to the load distributing member 280, and the head 215can be include mating threads or some other coupling feature. Thethreads on the stem 218 can have a standard threading, a multiple leadthreading, or some other suitable threading. For example, the threads onthe stem 218 can be threads of an example quick release fastener. Thehead 215 can be a threaded nut.

Optionally, the fastening device 210 can also include one or more othercomponents. For example, as shown in FIG. 2A, the fastening device caninclude load distributing member 212 and load distributing member 280.The optional load distributing member 212 can be mechanically coupled to(disposed on) the top surface of the cover flange 122, and/or theoptional load distributing member 280 can be mechanically coupled to(disposed on) the bottom surface of the base flange 132. Alternatively,the load distributing member 212 can be mechanically coupled to(disposed on) the bottom surface of the base flange 132, and theoptional load distributing member 280 can be mechanically coupled to(disposed on) the top surface of the cover flange 122. In certainexample embodiments, each load distributing member distributes the forceapplied to the top center portion of the load distributing member towardthe sides of the load distributing member to apply a substantially evendistribution of the force along the length of the load distributingmember.

Each load distributing member has a shape (e.g., length, width, pitch,height) that allows for a substantially even distribution of force alongthe length of the load distributing member when the force is applied tothe top center portion of the load distributing member. The loaddistributing members can be mechanically coupled to the cover flange 122and the base flange 132, as appropriate, using one or more of a numberof coupling methods. Such coupling methods can include, but are notlimited to, epoxy, fastening devices, compressive fittings, and slottedfittings.

In certain example embodiments, the bolt 209 swings through a slottedaperture 230 (a U-channel) in, at least, the load distributing member212 and the load distributing member 280. If the load distributingmember 212 and the load distributing member 280 do not extend beyond thecover flange 122 and the body flange 132, or if the load distributingmember 212 and the load distributing member 280 are not included in thesystem 200, then the slotted aperture 230 can be positioned in the coverflange 122 and the body flange 132.

As the head 215 (whether independently or as part of the bolt 209) isrotated in a direction (e.g., clockwise), the fastening device 210tightens and applies additional pressure to compress (apply acompressive force to) the load distributing member 212, the cover flange122, the body flange 132, and the load distributing member 280.Conversely, as the head 215 (whether independently or as part of thebolt 209) is rotated in an opposite direction (e.g., counterclockwise),the fastening device 210 loosens and removes pressure to compress(removes a compressive force to) the load distributing member 212, thecover flange 122, the body flange 132, and the load distributing member280.

FIG. 3 shows a cross-sectional side view of another example fasteningdevice 390 is used in accordance with certain example embodiments. Inone or more embodiments, one or more of the features shown in FIG. 3 maybe omitted, repeated, and/or substituted. Accordingly, embodiments offastening devices should not be considered limited to the specificarrangements of components shown in FIG. 3.

Referring to FIGS. 1-3, FIG. 3 shows a cross-sectional side view of asystem 300 that includes an example fastening device 390 to secure anexplosion-proof enclosure 103. In certain example embodiments, thefastening device 390 can include a fastener 310 and a fastener receiver340. The fastener 310 can include one or more of a number of components.Once such component can be a stem 318. The stem 318 can have a smoothouter surface. Alternatively, or in addition, the stem 318 can have oneor more features disposed on its outer surface. For example, the outersurface of the stem 318 can have a quick release mating thread (similarto the quick release fastener 109 described above with respect toFIG. 1) disposed along part of its outer surface.

The fastener 310 can also include a head 315 that is disposed at one endof the stem 318 and abuts a flange (e.g., cover flange 322, body flange332). The head 315 can be a threaded nut. The head 315 can be shapedand/or configured to accommodate one or more of a number of tools, whichcan be used to hold in place and/or move (e.g., rotate) the head 315.For example, the head 315, when looking from above, may be shaped like ahexagon (as for receiving a socket or a wrench). As another example, thehead 315 may have a slot (as for receiving a screwdriver) that traversesthe top surface. As another example, the head 315 can include aprotrusion from which two slotted wings extend laterally in oppositedirections, as with a wing nut.

In certain example embodiments, if the head 315 is removably coupled tothe stem 318 by quick release mating threads, the head 315 and/or thestem 318 can have a stop, as defined above with respect to FIGS. 1A and1B, that prevent the head 315 and the stem 318 from turning beyond acertain angle (e.g., 90°, 45°) relative to each other. In addition, orin the alternative, the head 315 and/or the stem 318 can have one ormore of a number of passages, as defined above with respect to FIGS. 1Aand 1B, that provide clearance for insertion and/or extraction of thehead 315 relative to the stem 318 when the mating threads are disengagedfrom each other.

Optionally, the fastener 310 can also include a base 319. In certainexample embodiments, at the end of the stem 318 opposite of where thehead 315 is disposed, the base 319 is disposed on the stem 318. The base319 can be used to secure (e.g., abuts against) a bottom portion of thefastener receiver 340, described below. If there is no fastener receiver340, then the base 319 can be used to secure a surface of a flange(e.g., the top surface of the cover flange 322, a bottom surface of thebase flange 332). The base 319 can extend laterally away from the stem318 at some angle (e.g., 90°, 120°, 45°). The base 319 can have any of anumber of shapes, including but not limited to a circle, a line, a bar,and a rectangle. The base 319 can extend laterally away from the stem318 symmetrically or asymmetrically.

If there is no base 319, the end of the stem 318 opposite of where thehead 315 is disposed can include one or more of a number of features(e.g., a slot, a hexagonal shape) that allows the stem 318 to berotated, using a tool, so that the stem 318 can be threadably coupled tothe head 315. If there is an base 319, the base 319 can have one or moreof such features.

The base 319, the head 315, and the stem 318 can be made as a singlepiece (as from a mold) and/or can be separate pieces that aremechanically coupled to each other in any of a number of couplingmethods, including but not limited to welding, compression fittings,mating threads, and slotted fittings. For example, the base 319 and thestem 318 can be a single piece that forms a “T”, while the head 315 ismovably (e.g., threadably) coupled to the stem 318. In certain exampleembodiments, at least one of the base 319 and the head 315 is movablycoupled to the stem 318. Examples of movable coupling methods caninclude, but are not limited to, mating threads, slotted fittings, and apin removably inserted into the stem 318. If mating threads are used,the mating threads can be any of a number of standard mating threadsmaking multiple rotations. Alternatively, the mating threads can bequick release threads, as described above with respect to FIGS. 2A-2C.

In certain example embodiments, the fastener receiver 340 receives partof the fastener 310 and is used to secure part of the enclosure. Thefastener receiver 340 can have one or more features that are used toreceive the fastener 310. An example of such a feature can be anaperture that traverses at least part of the fastener receiver 340. Forexample, as shown in FIG. 3, an aperture (hidden from view by the stem318) can traverse the entire height of the fastener receiver 340 at theapproximate radial center of the fastener receiver 340. In such a case,the aperture that traverses the fastener receiver 340 is substantiallythe same shape and size (cross-sectionally) as the cross-sectional shapeand size of the stem 318.

In addition, the cross-sectional shape and size of the aperture thattraverses the fastener receiver 340 can be substantially the same as theshape and size of an aperture that traverses an opposing flange (e.g.,the cover flange 322), where the opposing flange is different than theflange having the cavity 375, described below. The inner surface of thefastener receiver 340 that forms the aperture can be smooth, textured,and/or have some other feature (e.g., mating threads). The inner surfaceof the fastener receiver 340 that forms the aperture can have the sameand/or different features.

The fastener receiver 340 can also have one or more features that can beused to mechanically couple to the body flange 332 and/or the coverflange 322. For example, as shown in FIG. 3, the top portion of thefastener receiver 340 can have a cross-sectional shape and size that issubstantially the same shape and size as a cavity 375 in the body flange332. In certain example embodiments, the cavity that receives the topportion of the fastener receiver 340 is disposed in the cover flange 322rather than the body flange 332. In such a case, the orientation of thefastener receiver 340 is inverted from its position shown in FIG. 3. Insome cases, the cavity 375 can completely traverse the base flange 332(or the cover flange 322) and partially traverse the cover flange 322(or the base flange 332). Alternatively, the fastener receiver 340 canbe part of a single piece (as from a mold) with the flange (e.g., baseflange 332) on which the fastener receiver 340 is disposed.

The cavity 375 can be at least as long as the top portion of thefastener receiver 340. For example, as shown in FIG. 3, the cavity 375is longer (extends further upward into the body flange 332) than the topportion of the fastener receiver 340. The walls of the flange (e.g., thebody flange 332, the cover flange 322) that form the cavity 375 can besmooth, textured, and/or have some other feature (e.g., mating threads).Similarly, the outer surface of the top portion of the fastener receiver340 can have the same and/or different features. As an example, as shownin FIG. 3, the wall of the body flange 332 that forms the cavity 375 canhave mating threads 360 disposed thereon, and the outer surface of thetop portion of the fastener receiver 340 can have corresponding matingthreads 361 disposed thereon.

An example of another feature of the fastener receiver 340 that can beused to mechanically couple the fastener receiver 340 to the body flange332 and/or the cover flange 322 is a flared bottom portion. In such acase, as shown in FIG. 3, the flared portion of the bottom portionextend laterally away from the top portion of the fastener receiver 340,forming an angle with the top portion. Such an angle can be one or moreof a number of angles (e.g., 90°, 120°, 45°). In certain exampleembodiments, the angle formed by the flared portion of the bottomportion relative to the top portion can be such that the flared portionof the bottom portion of the fastener receiver 340 is substantiallyparallel to the bottom surface of the body flange 332 (or the topsurface of the cover flange 322, as appropriate) when the top portion ofthe fastener receiver 340 is mechanically coupled to the cavity 375.

When the fastener receiver 340 is disposed within the cavity 375, andwhen the fastener 310 is disposed within the aperture that traverses thefastener receiver 340, the base 319 and/or the head 315 can be adjustedrelative to the stem 318 to apply greater compressive force to thefastener receiver 340, the body flange 332, and the cover flange 322.For example, the head 315 can be a threaded nut that is threadablycoupled to an upper portion of the stem 318. When the head 315 isrotated in a certain direction (e.g., clockwise), the base 319 is pulledtoward the head 315. Conversely, as the head 315 is rotated in anopposite direction (e.g., counterclockwise), the base 319 is pushed awayfrom the head 315.

As a specific example, consider a case where the base 319 and the stem318 are a single piece that forms a “T”, while the head 315 isthreadably coupled, using quick release mating threads, to the stem 318.In such a case, the base 319 abuts against the fastener receiver 340,and the stem 318 traverses the aperture that extends through thefastener receiver 340. The adjacent surface on the fastener receiver 340can have a cam profile, so that as the combination of the stem 318 andthe base 319 is rotated and threadably coupled to the head 315, the stem318 is put in tension. Consequently, the cover flange 322 and the bodyflange 332 are drawn together, and the flame path 369 is closed. Basedon the cam profile of the fastener receiver 340, the quick releasemating threads can be, for example, ¼ or 1/10^(th) turn based on theelongation required for appropriate tension of the stem 318.

As another example, the fastener receiver 340 can be a cam fixture,similar to the cam fixture described in U.S. patent application Ser. No.13/793,672, entitled “Fastening Devices for Explosion-Proof Enclosures,”whose entire contents are hereby incorporated herein by reference. Forexample, the fastener receiver 340 can include a clearance slot, a camfeature, and an aperture (hidden from view by the stem 318).

In such a case, the clearance slot of the fastener receiver 340 canreceive the base 319 of the fastener 310 when the fastener 310 has beeninserted into the aperture of the fastener receiver 340. The aperture ofthe fastener receiver 340 can align with and have substantially the samesize and shape as an aperture that traverses the opposing flange (e.g.,the cover flange 322) from the flange (e.g., the base flange 332) intowhich the fastener receiver 340 is disposed. The shape and size of theclearance slot of the fastener receiver 340 relative to the base 319allow only a limited number of orientations for the base 319 to fitwithin the clearance slot. Such an alignment can coincide with couplingfeatures (e.g., quick release threads) disposed on the distal end of thestem 318, as well as the head 315.

Once the base 319 is fit within the clearance slot of the fastenerreceiver 340, the base 319 (and, thus, the rest of the fastener 310) canbe rotated outwardly along the cam feature until the base 319 reachesthe end of the cam feature. In certain example embodiments, the slopeand distance (e.g., amount of rotation) of the cam feature can coincidewith the slope and distance of the coupling features at the distal endof the stem 318.

Alternatively, if the stem 318 is fixedly coupled to the head 315, theslope and distance of the cam feature can coincide with the optimaltension of the stem 318 when the base 319 has been fully rotated withinthe cam feature. In such a case, the base 319 can be removably coupledto the stem 318. For example, the base 319 can be a pin that removablycouples (e.g., slides, threadably couples) to a receiving aperture atthe end of the stem 318

When the base 319 of the fastening device movably (e.g., rotatably)travels to the end of the cam feature, the stem 318 of the fastener 310is at an optimal tension. Such optimal tension of the stem 318 can also,or in the alternative, be a result of the distal end of the stem 318movably (e.g., rotatably, threadably) coupling to a coupling featuredisposed in the head 315. In any case, as a result, cover flange 322 andthe base flange 332 are forced toward each other and to close thedistance of the flame path 369.

The fastener receiver 340 can be made of one or more of a number ofmaterials. Examples of such materials can include, but are not limitedto, steel, rubber, nylon, and aluminum. In certain example embodiments,when the fastener receiver 340 is mechanically coupled to the fastener310 and one or both flanges, a flame path 369 between the cover flange322 and the body flange 332 can meet one or more applicable standards(e.g., flame path 369 is no greater than 0.0015 inches).

In certain example embodiments, the fastening device 390 of FIG. 3 andthe fastening device 110 of FIGS. 1A and 1B can be used with one or moreexample load distributing members, as described above with respect toFIGS. 2A-2C. In such a case, fewer fastening devices can be used aroundthe perimeter of the explosion-proof enclosure and still maintain theflame path for the enclosure.

Example embodiments of fastening devices for explosion-proof enclosuresresist explosion and/or hydrostatic forces by maintaining a flame pathwhere the cover flange and the body flange are coupled. Further, usingthe fastening devices described herein and other embodiments of thesefastening devices allows for efficient and effective coupling and/ordecoupling of the cover and the body of the explosion-proof enclosure.In addition, using example embodiments of fastening devices allows forincreased flexibility with regard to where components are positioned onthe cover and/or where conduit can be manually coupled to theexplosion-proof enclosure. Further, using example embodiments offastening devices for explosion-proof enclosures allows the flame pathto exist within the requirements of one or more standards forexplosion-proof enclosures.

Accordingly, many modifications and other embodiments set forth hereinwill come to mind to one skilled in the art to which fastening devicesfor explosion-proof enclosures pertain having the benefit of theteachings presented in the foregoing descriptions and the associateddrawings. Therefore, it is to be understood that fastening devices forexplosion-proof enclosures is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of this application. Althoughspecific terms are employed herein, they are used in a generic anddescriptive sense only and not for purposes of limitation.

What is claimed is:
 1. A system for fastening a cover to a body of anenclosure, comprising: a flange comprising at least one slotted aperturedisposed in a distal end of the flange; an opposing flange comprising atleast one anchor receiver, wherein the opposing flange abuts against theflange; and at least one fastening device, wherein each fastening deviceof the at least one fastening device comprises: an anchor hingedlydisposed in the at least one anchor receiver of the opposing flange; astem comprising a first end and a second end, wherein the first end iscoupled to the anchor, and wherein the second end is movably disposedwithin the at least one slotted aperture of the flange; and a headmovably coupled to the second end of the stem, wherein the head iscoupled to an outer surface of the flange adjacent to the at least oneslotted aperture when the at least one fastening device couples theflange and the opposing flange.
 2. The system of claim 1, wherein the atleast one fastening device further comprises: a load distributing memberdisposed on the outer surface of the flange, wherein the head abutsagainst the load distributing member.
 3. The system of claim 2, whereinthe load distributing member comprises a load distributing memberslotted aperture into which the stem is disposed when the at least onefastening device couples the flange and the opposing flange.
 4. Thesystem of claim 3, wherein the load distributing member slotted apertureis disposed within a portion of the load distributing member thatextends beyond the distal end of the flange, wherein the at least oneslotted aperture of the flange is substantially aligned with the loaddistributing member slotted aperture of the load distributing member,and wherein the stem is disposed within the at least one slottedaperture and the load distributing member slotted aperture when the atleast one fastening device couples the flange and the opposing flange.5. The system of claim 1, wherein the stem is disposed within the atleast one slotted aperture of the flange and the head abuts against theouter surface of the flange when the at least one fastening devicecouples the flange and the opposing flange.
 6. The system of claim 1,wherein the opposing flange further comprises an opposing flange slottedaperture, wherein the stem is disposed within the opposing flangeslotted aperture when the at least one fastening device couples theflange and the opposing flange.
 7. The system of claim 1, wherein theanchor remains disposed in the anchor receiver as the anchor hingedlyrotates.
 8. The system of claim 1, wherein the enclosure is anexplosion-proof enclosure, and wherein the flange and the opposingflange, when coupled by the at least one fastening device, forms a flamepath.
 9. The system of claim 1, wherein the anchor is shaped as a rodand is substantially perpendicular to the stem.
 10. A system forfastening a cover to a body of an enclosure, comprising: a flange; anopposing flange, wherein the opposing flange abuts against the flange; afirst load distributing member disposed on an outer surface of theflange; a second load distributing member comprising at least one anchorreceiver, wherein the second load distributing member is disposed on anouter surface of the opposing flange; and at least one fastening device,wherein each of the at least one fastening devices comprises: an anchordisposed in the at least one anchor receiver of the second loaddistributing member; a stem comprising a first end and a second end,wherein the first end is coupled to the anchor, and wherein the secondend is disposed within the at least one slotted aperture of the flange;and a head movably coupled to the second end of the stem, wherein thehead abuts against an outer surface of the first load distributingmember.
 11. The system of claim 10, wherein the first load distributingmember is among a plurality of first load distributing members, andwherein the second load distributing member is among a plurality ofsecond load distributing members.
 12. The system of claim 10, whereinthe first load distributing member comprises a first load distributingmember slotted aperture into which the stem is disposed when the atleast one fastening device couples the flange and the opposing flange.13. The system of claim 12, wherein the flange comprises a flangeslotted aperture that aligns with the first load distributing memberslotted aperture of the first load distributing member, wherein the stemis disposed within the flange slotted aperture and the first loaddistributing member slotted aperture when the at least one fasteningdevice couples the flange and the opposing flange.
 14. The system ofclaim 12, wherein the first load distributing member slotted aperture isdisposed within a portion of the first load distributing member thatextends beyond a distal end of the flange.
 15. The system of claim 12,wherein the second load distributing member comprises a second loaddistributing member slotted aperture into which the stem is disposedwhen the at least one fastening device couples the flange and theopposing flange.
 16. The system of claim 15, wherein the second loaddistributing member slotted aperture is disposed within a portion of thesecond load distributing member that extends beyond a distal end of theopposing flange.
 17. The system of claim 16, wherein the at least oneanchor receiver is disposed within the portion of the second loaddistributing member that extends beyond the distal end of the opposingflange.
 18. The system of claim 16, wherein the opposing flangecomprises an opposing flange slotted aperture that aligns with thesecond load distributing member slotted aperture of the second loaddistributing member, wherein the stem is disposed within the opposingflange slotted aperture and the second load distributing member slottedaperture when the at least one fastening device couples the flange andthe opposing flange.
 19. The system of claim 10, wherein the anchor isrotatably coupled to the anchor receiver.
 20. The system of claim 10,wherein the enclosure is an explosion-proof enclosure, and wherein theflange and the opposing flange, when coupled by the at least onefastening device, forms a flame path.